package cn.itcast.redisdemo.utils;

import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

/**
 * redis 借助redis生成全局唯一id
 */
@Component
public class RedisIdWorker {
    /**
     * 2022-01-01开始时间戳
     */
    private static final long BEGIN_TIMESTAMP = 1640995200L;
    /**
     * 序列号的位数
     */
    private static final int COUNT_BITS = 32;
    @Resource
    RedisUtil redisUtil;
    public long nextId(String keyPrefix) {
        // 1.生成时间戳
        LocalDateTime now = LocalDateTime.now();
        long timestamp = now.toEpochSecond(ZoneOffset.UTC) - BEGIN_TIMESTAMP;
        // 2.生成序列号
        // 2.1.获取当前日期，精确到天
        String date = now.format(DateTimeFormatter.ofPattern("yyyy:MM:dd"));
        // 2.2.自增长
        long count = redisUtil.incrBy("icr:" + keyPrefix + ":" + date,1);

        // 3.拼接并返回
        return timestamp << COUNT_BITS | count;
    }

  
}
